Natural stone walls and barriers date back hundreds of years, and have been used to defend against everything from enemy invasions and floods and fires to wild animals and neighbors. Although you may not need to defend your landscaping from an enemy hoard, you may need to defend it against dangerous floods and erosion. KRC Rock is prepared to help you build your own dry stack stone retaining wall to reduce soil erosion, stop polluted runoff, and create a beautifully primal stone accent to your garden landscape. Dry stack retaining walls are mortar-less, easy to build and allow for natural, slow drainage. If your house is built near or on a slope, a stone retaining wall can help defend against flooding and precious soil erosion.
Use these steps to build your own dry stack stone wall:
1. Check local codes before you begin digging (you may need a permit), although often you will not be bothered if you keep the retaining wall 3’ high or less.
2. The benefit of stone retaining walls is that they are mortar-less and that your “drainage system” comes built-in: water will usually seep through the cracks between the stones. Another advantage in building dry stack walls is that you do not have to sink a “footing” as you do when using concrete or stone and mortar.
3. Select stones that have at least two sides that are flat. The heavier the stones, the more stability you’ll have.
4. Plot out where the retaining wall will sit at the bottom of the slope, using stakes and string for a straight terrace, a garden hose for a curved one.
5. Dig a trench about 8”-10” deep, so that the first course of stone is fully or mostly submerged.
6. To calculate the necessary width of the trench, just remember the base of the retaining wall should be half the wall’s height. Angle the trench so that it inclines back slightly into the slope (2” for every 1’ of terrace height) – this will provide greater stability.
7. When you’ve almost penetrated down to the required depth, use a skimming motion to remove the remaining soil.
8. Terraces of natural stone are laid in “courses,” i.e., a horizontal row at a time. The first course of stones will consist of your largest, widest, longest, flattest stones (but save some for the final course, the “capstones”). Take the time to fit them as closely together as possible.
9. In terms of the height of the first course of stones and the following courses, you have two choices. If you’re aiming for a look of uniform rows, choose stones of the same height when laying a particular course. The other option is a more random look, in which you play each course by ear, using filler stones wherever necessary to make up for a difference in heights.
10. Check to ensure that the stones run level left to right. But because you’ve built a slight backwards slope into the trench’s base, your stones will slope down slightly from front to back. After completing this first course backfill with some of your excavated soil and any stones too small to use for building the retaining wall, and tamp it down.
11. In laying the next course of stones and those that follow, avoid lining up the joints over the joints of the course underneath. Again, backfill and tamp down after completing the course. As you place each stone, check that there’s as little wobble as possible. To counteract any wobbling, you may have to use small, flat rocks as “shims.” Use a mason's hammer to knick off stone fragments so as to achieve a better fit where possible.
13. Continue in the same manner with the third course and succeeding courses. By the time your terrace is half its planned height, you should start incorporating what are known as “deadmen.” The term refers to long stones laid perpendicularly across the wall, rather than parallel to all the other stones. Deadmen stones tie the retaining wall into the slope.
14. A hole is first dug into the slope to incorporate a deadman. Then one end of the deadman is set on the terrace, and the other end placed into the hole you’ve just created in the slope. A good rule of thumb is to provide at least one deadman per 16 square feet of exposed wall face.
15. When you’ve almost reached the desired height for your terrace, it’s time to place the capstones on top. Capstones serve both to help hold the stones under them in place and to provide a finished look to the retaining wall.
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